Federal agents armed with a search warrant shut down Free Radio 96.9 FM, the self-proclaimed oldest-running and most notorious unlicensed radio broadcaster in San Diego, in a midmorning raid yesterday.

About a dozen armed agents – some wearing shirts with the initials FCC, for Federal Communications Commission – served the warrant in South Park about 10 a.m. They seized amplifiers, computers, a transmitter and other equipment that effectively knocked the station off the air, witnesses said.

Agents also climbed onto the roof of a house next to a wooden shack that served as the studio for the station, removing a 43-foot-tall antenna in sections and putting it in a van.

Dayn Reardon, 22, was one of several supporters of the station who watched the raid.

"This is a fight over free speech," said Reardon, who vowed that staff and loyal listeners will hold fundraisers and buy new equipment to get the station back on the air at an undisclosed location.

The U.S. Attorney's Office declined comment yesterday; no one from the FCC returned phone calls seeking comment.

Free Radio, which had illegally broadcast for three years out of the private residence on Bancroft Street, could also be heard on a legal Internet simulcast at www.pirate969.org.

The station was not streaming on the Internet yesterday afternoon.

The FCC has said it investigates underground stations if it receives enough complaints from commercial broadcasters or the public that the illegal signal is interfering with legitimate transmissions.

Operators of Free Radio, if convicted, could face a one-year prison sentence and a $10,000 fine for operating an unlicensed outlet.

The station's founder, who identified himself only by his radio DJ name Bob Ugly, said he would try to get Free Radio back on the air in a month.

"The station never received any interference complaints," he said. "We went on the air illegally because it was impossible for us to get a license."

With its eclectic mix of everything from political commentaries and rock music to lilting gospel tunes, the station enjoyed a wide reach, from Interstate 8 to the north, Interstate 805 to the east and Tijuana to the south.

Station supporter Lori Thurman, 20, said Free Radio had a popular following. "It was truly democratic," she said. "There were no ads."

Charlie Darling, one of the more than 20 part-time disc jockeys working for free at the station, said rent and utilities were paid for through donations by station announcers.

Yesterday's raid hardly came as a surprise to station personnel, since the FCC had posted a warning on a door at the radio's makeshift studio a month ago, Darling said.

With Free Radio's sudden demise, there still are a handful of local pirate stations illicitly beaming their signals to an unknown number of listeners.

These include Chronic Radio, which uses Free Radio's FM location during its down hours.

Another station, Radioactive, can be heard on the Internet, where its Web stream is picked up by someone apparently unknown to the station who then broadcasts it at FM 106.9.

There are dozens of pirate stations currently programming in the United States, among them Atomic Frog, Betty Boop Radio, Orbital Mind Control Satellite and Johnny Weasel, according to Pirate Radio Central, a Web site that tracks the trend.

The zenith of pirate radio operations in San Diego County was probably in the early 1990s, when hundreds of small stations operated out of basements and garages here, according to estimates by ham radio operators at the time.